Members of Congress are lobbying against Chinese handset maker Huawei’s plans to enter the US market via AT&T’s discount subsidiary Cricket, demanding that federal regulators stop the move on national security grounds.

Reuters reported Tuesday that US lawmakers are urging the nation’s second-largest carrier AT&T to cut commercial ties to Huawei and oppose plans by state-owned carrier China Mobile to enter the US market because of national security concerns.

Sources told the news gathering organization that AT&T earlier this month was forced to scrap a plan to offer its customers Huawei handsets. National security experts are concerned about the possibility of any data from Huawei phones, like location information, being secretly sent to Chinese government intelligence services.

From the report:

The lawmakers are also advising US firms that if they have ties to Huawei or China Mobile, it could hamper their ability to do business with the US government, one aide said, requesting anonymity because they were not authorized to speak publicly.

One of the commercial ties senators and House members want AT&T to cut is its collaboration with Huawei over standards for the high-speed next generation 5G network, the aides said. Another is the use of Huawei handsets by AT&T’s discount subsidiary Cricket, the aides said.

“We hope that China and the United States can work hard together to maintain the healthy and stable development of trade and business ties. This accords with the joint interests of both,” Chinese foreign ministry spokesman Lu Kang said on Tuesday.

Huawei sells its equipment through more than 45 of the world’s top 50 carriers. However, the company is often suspected of enabling surveillance in its devices.